Why is "defer" different from "snooze"? Both indicate picking a time to deal with the email.
Defer forces you to book a time in your calendar instead of "snoozing" the message just so that it reappears later. Actually, snoozing was one of the most exciting features I saw in Mailbox, but after using it heavily I realised I get plenty of messages on Monday morning back to inbox and I just snooze them again. It turned to be a complete disappointment for me
Or maybe have up to X "snooze slots" so that you cant snooze everything and you snooze things that truly dont deserve to be deleted. And you would have to empty a slot by dealing with a snoozed message to be able to snooze a new one.